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  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      //   class Father {
      //     constructor() {}
      //     money() {
      //       console.log(100);
      //     }
      //   }
      //   class Son extends Father {}
      //   var son = new Son();
      //   son.money();

      class Father {
        constructor(x, y) {
          this.x = x;
          this.y = y;
        }
        sum() {
          console.log(this.x + this.y);
        }
      }
      class Son extends Father {
        constructor(x, y) {
          super(x, y); //调用父类中的构造函数
        }
      }
      var son = new Son(1, 2);
      var son1 = new Son(11, 22);
      son.sum();
      son1.sum();
    </script>
  </body>
</html>
